On 25 March 2025 05:53:30 GMT, Robert Chapin <p...@miqrogroove.com> wrote:
>I may have over-simplified the examples. Comparing $input === 'yes' will have
>the same result whether $input is null or 'none' or an empty string. So not
>implying a result type, just want to compare a literal or other variable to
>$input even when not declared.
The examples are fine, I think, but perhaps I didn't explain mine clearly
enough.
My point is that because null is not going to be coerced by the language to
either 'on' nor 'off', there's an implied default depending how you write the
expression.
The following both evaluate to true for an input of 'on', and false for an
input of 'off', but give different results for null:
$input === 'on'
$input !== 'off'
The implied default in the first is 'off', but in the second it's 'on'.
>A different example could be if (coalesce($_POST['tick']) > 10) return;
In this case, the implied default is 0. It's less risky, because the coercion
from null to int is straightforward. The following all imply a default of zero:
if (coalesce($_POST['tick']) >= 10) return;
if (coalesce($_POST['tick']) != 10) return;
if (coalesce($_POST['tick']) !== 10) return;
if (coalesce($_POST['tick']) > 0) return;
if (coalesce($_POST['tick']) >= 0) return;
if (coalesce($_POST['tick']) != 0) return;
But this doesn't:
if (coalesce($_POST['tick']) !== 0) return;
By specifying the default explicitly, we don't have to examine the expression
carefully to see what's implied.
I don't know if I'd go as far as banning a single-argument coalesce, but I
would definitely discourage its use.
Rowan Tommins
[IMSoP]
